Convection heating element
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Solution Overview
Problem
Convection ovens face inefficiencies due to high watt density requirements for heating elements, which reduce cooking space and hinder heat transfer from the heating elements to air, leading to thermal inefficiencies and potential damage from excessive heat absorption by the rear wall and shroud.
Innovation Solution
A convection heating element design featuring concentric loops in parallel planes with axial and radial/lateral gaps, allowing for improved air flow and heat transfer efficiency by exposing more of the heating element's surface area to air flow, reducing the need for high watt density and minimizing fan power requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional heating element design is used, then heating function is provided, but thermal efficiency is limited due to inadequate heat transfer to air
Solution Approach 1:
The heating element is segmented into multiple concentric loops with gaps between them, allowing air to flow through and over the heating elements more effectively. This segmentation increases the surface area exposed to air flow and improves convective heat transfer, directly addressing the thermal efficiency limitation.
Solution Approach 2:
The heating element transitions from a conventional planar or single-loop design to a three-dimensional concentric loop structure with axial and radial gaps. This dimensional arrangement creates multiple flow paths for air and increases the effective heat transfer surface area, enhancing the heat transfer rate without increasing watt density.
2Power
If higher watt density is used to attain requisite heat setting, then heating performance is improved, but cooking space decreases due to larger diameter coils
Solution Approach 1:
The heating element is divided into multiple concentric loops of different diameters. This segmentation allows the total heating power to be distributed across a larger effective surface area, reducing the watt density requirement while maintaining the requisite heat setting. The concentric arrangement maximizes the use of available space without requiring larger diameter coils.
Solution Approach 2:
Multiple heating loops are nested concentrically within the oven cavity, with each loop positioned at a different radius from the center. This nesting arrangement allows all loops to coexist in a compact configuration, providing high total heating power while minimizing the overall diameter and preserving cooking space.
3Device complexity
If conventional heating element design obstructs air flow, then structural simplicity is maintained, but heat transfer to air is diminished
Solution Approach 1:
The heating element is segmented into multiple concentric loops with intentional gaps between them. These gaps create channels that guide air flow through the heating element structure, ensuring that air contacts the heating surfaces more effectively. This segmented design improves heat transfer without significantly increasing structural complexity.
Solution Approach 2:
The gaps between concentric loops act as intermediaries that facilitate air flow through the heating element assembly. These gaps allow air to penetrate and flow through the structure, enhancing convective heat transfer while maintaining a relatively simple overall design that integrates with the existing oven architecture.
4Power
If rear wall and shroud absorb excessive heat, then heating function is achieved, but thermal damage risk increases
Solution Approach 1:
The segmented concentric loop structure distributes heat generation across multiple surfaces exposed to air flow. This segmentation promotes more uniform heat distribution and reduces localized overheating of the rear wall and shroud, lowering the risk of thermal damage while maintaining effective heating power.
Solution Approach 2:
The gaps between concentric loops serve as intermediaries that facilitate efficient heat transfer from the heating elements to the air. By improving convective heat transfer, these gaps reduce the residence time of hot air near the rear wall and shroud, thereby reducing the amount of heat absorbed by these components and lowering thermal damage risk.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design enhances thermal efficiency by increasing heat transfer from the heating element to air, reducing energy consumption, and minimizing the risk of thermal damage to the oven components, while allowing for a more compact cooking space.
Implementation Method 1
The heating element generally is made of an electrical-resistant coil that converts electrical energy into heat
Implementation Method 2
the fan blows air over the heating element to heat the air as it is expelled into the cavity
Data Source
AI summary
A convection oven includes a heating element made of a single coil formed into a pair of concentric loops. The concentric loops are disposed in parallel planes to improve the thermal efficiency and power requirements of the convection oven.